Step 1: What to do

Most modern day mice are use a laser to detect movement. All you have to do is take a sticky note or piece of tape, and then cover the laser. It's that simple

If the mouse is an old school ball mouse, turn it upside down, and the ball will drop to the inside of the mouse. Then just cover the hole with a piece of tape.

Make sure to right down April Fools on the tape or whatever!

Step 2: The reaction

People will freak when their mouse mysteriously doesn't work! It's amazing, I did this to a bunch of my teachers last year, and they flipped out trying to find an unplugged cord or something thats wrong with the computer. Some will think that their computer is even frozen.

This isn't nearly devious enough. Everyone expects tape or something similiar on the bottom. But to really drive someone insane you:1) place a clear piece of tape over the sensor opening2) trim it with a razor so it looks completely organic 3) poke the tape with a needle onceThis causes enough laser light to reflect so that the mouse moves, but it's incredibly jerky and unusable. They'll be cussing, unplugging, replacing batteries, restarting, etc etc, and every time they look at the bottom of the mouse they can't tell it's been tampered with. I've done this numerous times with outstanding success :D. Enjoy!

this is the better way, i did this to two of my teachers on april fools day and they both turned the mouse over and noticed it :(but also i looped a peice of tape so it was sticky all around and put it on the hearing end of his phone and when he picked up his phone with another tacher on the line he said what the f*** under his breath :DD!!!!

I don't know about that. Most LED mice don't turn the LED on unless they have an actual connection with the PC (except for wireless ones). You'd have to install a microcontroller set up to sync with the mouse so it lights up.

Another great Prank is take a wireless usb mouse and plug it into the victims computer and when ever they try to use their mouse use yours to interfere click random things open or close thing down or if you do it to a teacher that uses power point to teach advance the slide show randomly

won't work with a cordless mouse - usually your first response is to check that it has battery by looking at the bottom to see if the light is on. in fact. I know many people who do that with corded mice too, to check for obstructions like this...

Cordless mouse: best prank is to put a piece of paper blocking a battery, making sure to leave enough to write "April Fools" on it. Corded mouse: Paper ball in the optical with a tag sticking out, again write "April Fools" on it. Old corded mouse: take the ball out, place in tagged note with April Fools and instructions to hide the ball. Hide the ball in an easy place to find it, such as an empty coffee cup or in the pen-holder.